Google has admitted it is behind the Webdriver Torso web account, an unlikely internet sensation which has mystified and delighted web users.

The mystery began when a series of seemingly pointless 11-second videos - all showing a series of blue and red rectangles - were uploaded in their thousands to YouTube.

Speculation was rife about who was behind the enigmatic postings and what they could mean.

Aliens and spies were mooted.

But now it seems that the reality behind the Webdriver Torso mystery is more mundane - it is one of many tests channels used by YouTube to ensure video quality.

The content of the video is meaningless, just a random set of sounds and visuals picked because they were easy to create, according to a YouTube source.

By comparing the uploaded video with the original file, the team is able to assess whether they are being uploaded in the same quality.

Mystery solved

In an official statement, Google said: "We're never gonna give you uploading that's slow or loses video quality, and we're never gonna let you down by playing YouTube in poor video quality.

"That's why we're always running tests like Webdriver Torso."

Its light-hearted statement echoes 1980s pop star Rick Astley's hit song Never Gonna Give You Up in reference to a recent Webdriver Torso video which showed the singer in silhouette.

That in turn is a reference to Rickrolling, one of the internet's most famous memes which linked people to a video of the singer via a masked link.

The Webdriver Torso mystery was finally solved by website Engadget following revelations that Webdriver was part of a network called ytuploadtestpartner_torso, which in turn was associated with social media accounts that name-dropped several Google employees based at its Zurich office.

Engadget confronted Google with its findings and the search engine confessed.

Not spies

Perhaps we shouldn't relax just yetStephen Beckett, BBC Click

Wired magazine was the first to spot the Webdriver Torso phenomenon in February, as part of a feature on bizarre YouTube clips.

The technology press quickly became obsessed with the story, with a variety of theories postulated, including that the videos were part of an advertising campaign by aliens or a digital version of spies' numbers stations, used during the Cold War to decode messages.

Each of the almost 80,000 clips - uploaded over a seven-month period - followed the same pattern - 10 slides, each with a red rectangle, a blue rectangle and a computer-generated tone.

The BBC conducted its own investigation, led by BBC Click producer Stephen Beckett. He asked Google if it was behind the mystery at the end of May but, at the time, the firm declined to comment.

"I can't deny I'm not disappointed that we haven't discovered extra-terrestrial life, or cracked the communications of a clandestine spying ring," he said.

"While the truth may be a little more down to earth, with all the attention now is the perfect time for aliens and spies to start communicating discreetly via rectangles and Rick Astley memes. Perhaps we shouldn't relax just yet."